Hydroxyaromatic-aldehyde polymers, and in particular phenol-formaldehyde resole polymers, are of utility in a wide range of applications due to their excellent physical properties, including their durability, water resistance, bond strength, and the like, as well as their low cost and ease of manufacture and use. Phenol-formaldehyde resole polymers have accordingly been used in the manufacture of products as diverse as laminates, consolidated wood products, and fiberglass insulation materials.
While a wide variety of hydroxyaromatic-aldehyde polymers have been developed and are suitable for their intended purposes, environmental and industry standards demand ever-increasing improvement in both environmental compliance and physical properties of the polymers. Reduction in aldehyde (particularly formaldehyde) emissions has proved particularly difficult without significantly adversely affecting the advantageous properties of the polymers, cost, and/or manufacturing time. For example, formaldehyde scavengers such as urea, ammonia, melamine, various primary and secondary amines, dicyandiamide, and other amino-based modifications have been added to resoles. These are typically post-added to the polymer or at the customers' plant, resulting in low efficiencies. Post-addition of urea can cause trimethylamine odors, which arise from incomplete reaction of urea. Post-addition of ammonia as a scavenger can lead to lower water dilutability, unwanted precure, and ammonia odor.
Additionally, increasing costs for raw materials, such as phenol, and a global push to seek out environmentally friendly chemistries have led to the search for alternatives to remain competitive in the market.
Further, production processes for phenolic compounds often produce by-product material with limited uses. For example, bisphenolic production processes often have by-products called “stillbottoms” that have limited commercial and industrial use or are difficult to process into useful materials. For example, bisphenolic stillbottoms must be further refined before they are useable in the synthesis of a novolac polymer, which refining process may include extreme temperatures, reduced pressures and in the presence of an alkaline catalyst, to recover useful materials.
There is accordingly a need for hydroxyaromatic-aldehyde polymers and methods that will lower or remove hydroxyaromatic and aldehyde (particularly formaldehyde) emissions from hydroxyaromatic-aldehyde while maintaining or improving advantageous physical properties, such as moisture resistance, that can be used in the preparation of useful articles.